Absolute Identification is a seemingly simple cognitive task that provides researchers with a number of interesting and complex phenomena. The task provides evidence towards an information processing capacity, which Miller (1956) popularised with his magical number 7±2 – a number of which he suggested is reminiscent of the number of unidimensional items (or chunks in short term memory) that an individual should be able to learn to perfectly identify. This limit has long since been accepted as a truism of absolute identification research, with much further model development accepting this as a known intrinsic “quirk” of absolute identification performance. This thesis begins with results that are in stark contrast to Miller’s findings – we find that given moderate practice, participants are able to improve their performance significantly. The following chapters describe further investigation into this contrary result, and provide an overview of current models of AI performance. Through a series of published and submitted papers, we investigate the possibility that rather than disproving Miller’s theory of an information processing capacity, we might have further refined the absolute identification paradigm. Close examination of common stimuli used in absolute identification tasks reveals that while common stimuli such as line lengths and dot separation are physically unidimensional, the psychological representation of these stimuli may be multidimensional. Interestingly, the sole stimulus modality that did not exhibit learning effects – tone loudness - did not appear to be represented on multiple dimensions. Without the assumption of uni-dimensionality, we cannot suggest the results are due to some difference in information processing capacity, but are rather more likely an artefact of stimulus perception. These results have significant consequences for the future of absolute identification research: it would appear that absolute identification researchers should restrict their use of stimulus modalities to only tones varying in loudness.